kernel/kstack_erase.c:34:56: sparse: sparse: incorrect type in argument 3 (different address spaces)

kernel/kstack_erase.c:34:56: sparse: sparse: incorrect type in argument 3 (different address spaces)

[kernel test robot]

Hi Kees,

First bad commit (maybe != root cause):

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   6a68cec16b647791d448102376a7eec2820e874f
commit: 32e42ab9fc88a884435c27527a433f61c4d2b61b sched/task_stack: Add missing const qualifier to end_of_stack()
date:   5 days ago
config: loongarch-randconfig-r112-20250801 (https://download.01.org/0day-ci/archive/20250801/202508011029.WGeVHkWa-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 8f09b03aebb71c154f3bbe725c29e3f47d37c26e)
reproduce: (https://download.01.org/0day-ci/archive/20250801/202508011029.WGeVHkWa-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202508011029.WGeVHkWa-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> kernel/kstack_erase.c:34:56: sparse: sparse: incorrect type in argument 3 (different address spaces) @@     expected void * @@     got void [noderef] __user *buffer @@
   kernel/kstack_erase.c:34:56: sparse:     expected void *
   kernel/kstack_erase.c:34:56: sparse:     got void [noderef] __user *buffer
>> kernel/kstack_erase.c:54:35: sparse: sparse: incorrect type in initializer (incompatible argument 3 (different address spaces)) @@     expected int ( [usertype] *proc_handler )( ... ) @@     got int ( * )( ... ) @@
   kernel/kstack_erase.c:54:35: sparse:     expected int ( [usertype] *proc_handler )( ... )
   kernel/kstack_erase.c:54:35: sparse:     got int ( * )( ... )

vim +34 kernel/kstack_erase.c

964c9dff009189 kernel/stackleak.c Alexander Popov  2018-08-17  23  
0df8bdd5e3b3e5 kernel/stackleak.c Xiaoming Ni      2022-01-21  24  #ifdef CONFIG_SYSCTL
78eb4ea25cd5fd kernel/stackleak.c Joel Granados    2024-07-24  25  static int stack_erasing_sysctl(const struct ctl_table *table, int write,
0df8bdd5e3b3e5 kernel/stackleak.c Xiaoming Ni      2022-01-21  26  			void __user *buffer, size_t *lenp, loff_t *ppos)
964c9dff009189 kernel/stackleak.c Alexander Popov  2018-08-17  27  {
964c9dff009189 kernel/stackleak.c Alexander Popov  2018-08-17  28  	int ret = 0;
964c9dff009189 kernel/stackleak.c Alexander Popov  2018-08-17  29  	int state = !static_branch_unlikely(&stack_erasing_bypass);
964c9dff009189 kernel/stackleak.c Alexander Popov  2018-08-17  30  	int prev_state = state;
0e148d3cca0dc1 kernel/stackleak.c Thomas Weißschuh 2024-05-03  31  	struct ctl_table table_copy = *table;
964c9dff009189 kernel/stackleak.c Alexander Popov  2018-08-17  32  
0e148d3cca0dc1 kernel/stackleak.c Thomas Weißschuh 2024-05-03  33  	table_copy.data = &state;
0e148d3cca0dc1 kernel/stackleak.c Thomas Weißschuh 2024-05-03 @34  	ret = proc_dointvec_minmax(&table_copy, write, buffer, lenp, ppos);
964c9dff009189 kernel/stackleak.c Alexander Popov  2018-08-17  35  	state = !!state;
964c9dff009189 kernel/stackleak.c Alexander Popov  2018-08-17  36  	if (ret || !write || state == prev_state)
964c9dff009189 kernel/stackleak.c Alexander Popov  2018-08-17  37  		return ret;
964c9dff009189 kernel/stackleak.c Alexander Popov  2018-08-17  38  
964c9dff009189 kernel/stackleak.c Alexander Popov  2018-08-17  39  	if (state)
964c9dff009189 kernel/stackleak.c Alexander Popov  2018-08-17  40  		static_branch_disable(&stack_erasing_bypass);
964c9dff009189 kernel/stackleak.c Alexander Popov  2018-08-17  41  	else
964c9dff009189 kernel/stackleak.c Alexander Popov  2018-08-17  42  		static_branch_enable(&stack_erasing_bypass);
964c9dff009189 kernel/stackleak.c Alexander Popov  2018-08-17  43  
964c9dff009189 kernel/stackleak.c Alexander Popov  2018-08-17  44  	pr_warn("stackleak: kernel stack erasing is %s\n",
62e9c1e8ecee87 kernel/stackleak.c Thorsten Blum    2024-12-22  45  					str_enabled_disabled(state));
964c9dff009189 kernel/stackleak.c Alexander Popov  2018-08-17  46  	return ret;
964c9dff009189 kernel/stackleak.c Alexander Popov  2018-08-17  47  }
1751f872cc97f9 kernel/stackleak.c Joel Granados    2025-01-28  48  static const struct ctl_table stackleak_sysctls[] = {
0df8bdd5e3b3e5 kernel/stackleak.c Xiaoming Ni      2022-01-21  49  	{
0df8bdd5e3b3e5 kernel/stackleak.c Xiaoming Ni      2022-01-21  50  		.procname	= "stack_erasing",
0df8bdd5e3b3e5 kernel/stackleak.c Xiaoming Ni      2022-01-21  51  		.data		= NULL,
0df8bdd5e3b3e5 kernel/stackleak.c Xiaoming Ni      2022-01-21  52  		.maxlen		= sizeof(int),
0df8bdd5e3b3e5 kernel/stackleak.c Xiaoming Ni      2022-01-21  53  		.mode		= 0600,
0df8bdd5e3b3e5 kernel/stackleak.c Xiaoming Ni      2022-01-21 @54  		.proc_handler	= stack_erasing_sysctl,
0df8bdd5e3b3e5 kernel/stackleak.c Xiaoming Ni      2022-01-21  55  		.extra1		= SYSCTL_ZERO,
0df8bdd5e3b3e5 kernel/stackleak.c Xiaoming Ni      2022-01-21  56  		.extra2		= SYSCTL_ONE,
0df8bdd5e3b3e5 kernel/stackleak.c Xiaoming Ni      2022-01-21  57  	},
0df8bdd5e3b3e5 kernel/stackleak.c Xiaoming Ni      2022-01-21  58  };
0df8bdd5e3b3e5 kernel/stackleak.c Xiaoming Ni      2022-01-21  59  

:::::: The code at line 34 was first introduced by commit
:::::: 0e148d3cca0dc1a7c6063939f6cb9ba4866c39a7 stackleak: Use a copy of the ctl_table argument

:::::: TO: Thomas Weißschuh <linux@weissschuh.net>
:::::: CC: Kees Cook <keescook@chromium.org>

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